In golf, the angle between the hosel or club axis and a horizontal plane is called the lie angle. Ideally, the sole of the clubhead should be perfectly parallel with the ground at the moment the face of the clubhead impacts the ball. If the heel of the clubhead is higher than the toe at the moment of impact, the ball will hook or slice, depending upon whether the golfer is left or right-handed, respectively. If the toe of the clubhead is elevated with respect to the heel at said moment, the ball will deviate from its intended path of travel in the opposite direction. Moreover, the effect of an incorrect lie angle at the moment of impact is amplified as the angle of the clubhead face increases, i.e., the effects of an improper lie angle are less for putters and increasingly important as the loft angle of the clubhead face increases.
Most golfers simply use trial and error techniques and hope to eventually learn how to hold their clubs at the proper lie angle. Others employ a device shown in U.S. Pat. No. 4,580,350 to Fincher. That device includes a linear in configuration bubble tube that is releasably secured to a clubhead face. An alignment ridge mates with a preselected groove formed in the clubhead face to hold the tube level with respect to the face, and a flat spring releasably holds the bubble tube to said face. When the bubble in the bubble tube is centered, the golfer knows that the heel and toe of the clubhead are lying in a common horizontal plane. Thus, the golfer believes that if the ball is struck while the clubhead is being held in the indicated plane, then the ball will neither hook nor slice when driven. Experience, however, has shown that the use of the Fincher device still results in hooks and slices, but the source of the problem has remained unidentified for years.
The prior art, taken as a whole, neither teaches nor suggests what bedevils the Fincher device, and thus of course contains no hint as to how the limitations of that device could be overcome.